Did you ever wonder why there are air bubbles in your water?

Kansas Department of Health & Environment explains that as water cools it dissolves oxygen and holds it. As water warms it depletes oxygen.

Certain times of the year, water cools down in the water towers and absorbs oxygen from the air. Then as it comes into the distribution system it starts to warm up and as people draw it into their homes it warms up even more so. As you draw a glass of water from the tap the warmer water starts releasing the oxygen in the form of air bubbles.

Certain types of aerators on faucets will cause air to form in a glass of water.

There is no health hazards and it should not be a concern.